This website requires a browser which supports HTML5.
Some elements of this site will not work correctly until you upgrade your browser.
Event
clock
as
as
seen
by
astronaut
in
the
spaceship.
Event
clock
as
as
seen
by
observer
watching
spaceship
go
by.
Special
Relativity:
Moving
Clocks
Show/hide
pulse
path.
Show/hide
pulse
path.
The
astronaut
on
board
the
ship
is
at
rest
relative
to
the
time
event
clock.
The
light
pulses
travel
at
the
speed
of
light
c.
The
time
duration
of
the
event
is
the
time
taken
by
the
pulse
to
go
from
bottom
to
top
mirrors.
The
controller
observes
the
spaceship
passing
by.
He
will
not
see
the
up
and
down
motion
of
the
light
pulse
but
rather
a
stretched
out
triangular
path
of
longer
distance.
To
preserve
the
universal
fact
that
the
speed
of
light
is
constant
when
measured
from
any
frame
of
reference
the
event
time
must
be
longer
as
measured
from
the
observer’s
reference
frame.
Moving
clocks
go
slow!
Click
pictures
for
notes.